Hair condition, in particular hair disorders, have traditionally been assessed by clinical inspection and a number of invasive methods including a pull-test, a trichogram obtained from extraction of approximately hundred hairs for microscopic inspection of their roots, and patomorphology which uses biopsy after extraction of skin tissue for microscopic inspection.
In 2006, it was proposed by Ross, E K, Vincenzi, C I, and Tosti, A. that a dermoscope or videodermoscope, traditionally used for skin lesion observations, may be used for diagnosing hair disorders. Since then their method, usually referred to as trichoscopy, has gained some popularity due to its non-invasiveness. A number of studies have been carried out to provide guidelines for disease diagnosis based on visual, qualitative inspection of the videodermosopy images by a trained dermatologist doctor. Visual trichoscopy has generally focused on setting the initial diagnosis based on certain characteristic features observed in the dermoscopy images of the scalp, such as broken hair, yellow dots, black dots, tulip hair, arborizing vessels, etc. This qualitative inspection of the videodermosopy images did not provide tools to, for example, clearly distinguish between most common conditions like to distinguish Androgenetic alopecia (AGA) from diffuse Alopecia areata (AA) and Telogen effluvium (TE), precisely measure advancement of AGA, or to precisely measure therapy efficiency once medication is introduced.
The term trichoscopy may further be used to refer to a technique used in the assessment of hair condition, examination of symptoms of hair disorder, diagnosis of hair disorders, and monitoring hair treatment efficiency. Trichoscopy uses a microscopic camera, a so-called videodermoscope to register high resolution images of hair and scalp or other skin. Such images may further be referred to as videodermoscopy images. In known methods, the videodermoscopy images are subject to manual or computer-assisted analysis to try to identify all hair shafts and measure hair diameters. A statistical analysis of images registered before and after the treatment allows to assess the response to treatment in terms of, for example, hair number or hair density, hair thickness and hair volume. In order to try to detect therapeutic effects in the pre- and post-image comparison, a multiple micro tattoo marking is used to help to identify the same skin location and field of view, with the aim of positioning the videodermoscope at the same position after the treatment as before. Known methods suffer from various limitations. For example, it may be difficult or even impossible to draw any conclusions if the overall hair density change is statistically insignificant. Also, currently used methods do not allow to ensure that the pre- and post-images represent really the same skin area. Further, with known methods, the precision of the analysis relies strongly on exactly the same positioning of the camera on the skin and the same field of view.
Known trichoscopy techniques used in the assessment of hair condition, examination of symptoms of hair disorder, diagnosis of hair disorders and monitoring hair treatment efficiency thus still suffer from various limitations.